The principal objective of this project is to determine the electronic and stereochemical structures of the metal and the ligand in hemoproteins. Single crystals of CoMb17O2 will be grown and epr spectra measured at liguid nitrogen temperature to obtain the O17 hyperfine tensor. Similar experiments with CoMbCO13 will be conducted to determine the C13 hyperfine tensor. The two-state MWC model will be applied to CoHb. The chief goal here is to determine how much the R - T allosteric equilibrium is affected by the metal atom substitution. Nmr will be used to study phosphate binding sites and to determine contact shifts of various nuclei. It will also be employed to study Hb-Co2 equilibria.